Radio terminal, radio base station, channel signal forming method and channel signal receiving method

ABSTRACT

A base station is disclosed, including an information size adjusting section configured to adjust a size of control information based on a first basic information size of control information mapped on a user equipment (UE) specific search space in a first component carrier. The base station also includes a transmitter configured to transmit the control information mapped on the UE specific search space. A first determination method for determining the first basic information size is different from a second determination method for determining a second basic information size of control information mapped on a common search space in the first component carrier. The first determination method for determining the first basic information size is different from a third determination method for determining a third basic information size of control information mapped on a search space in a second component carrier that is different from the first component carrier.

BACKGROUND Technical Field

The present invention relates to a radio terminal, radio base station,channel signal forming method and channel signal receiving method.

Description of the Related Art

In 3GPP LTE, OFDMA (Orthogonal Frequency Division Multiple Access) isemployed as a downlink communication method. In a radio communicationsystem adopting 3GPP LTE, a base station transmits a synchronizingsignal (synchronization channel: SCH) and a broadcast signal (broadcastchannel: BCH) using prescribed communication resources. A terminal firstsynchronizes with a base station by capturing the SCH. Then, theterminal acquires parameters that are specific to that base station (forexample, the frequency bandwidth) by reading BCH information (seeNon-patent Literature 1, 2 and 3).

Also, after the terminal acquires base station-specific parameters, theterminal sends a connection request to the base station, and, by thismeans, establishes communication with the base station. When necessary,the base station transmits control information to the terminal, withwhich communication has been established, using a PDCCH (PhysicalDownlink Control CHannel).

The terminal performs “blind detection” for the received PDCCH signal.That is, a PDCCH signal includes a CRC (Cyclic Redundancy Check) part,and, at a base station, this CRC part is masked by the terminal ID ofthe target terminal. Thus, until a terminal demasks the CRC part of areceived PDCCH signal with the terminal's terminal ID, the terminalcannot decide whether or not the PDCCH signal is for that terminal. Inthis blind detection, if the result of demasking is that CRC calculationis OK, the PDCCH signal is decided to be sent for the terminal.

Also, control information sent by a base station includes assignmentcontrol information including, for example, information about resourceswhich a base station allocates to a terminal. A terminal needs toreceive both downlink assignment control information and uplinkassignment control information which have a plurality of formats.Although downlink assignment control information which a terminal shouldreceive can be defined in a plurality of sizes depending on thetransmitting antenna control method and frequency allocation method at abase station, some of these downlink assignment control informationformats (hereinafter simply referred to as “downlink assignment controlinformation”) and uplink assignment control information formats(hereinafter simply referred to as “uplink assignment controlinformation”) are transmitted using PDCCH signals of the same size. APDCCH signal includes type information of assignment control information(for example, a 1 bit flag). Thus, even if the size of a PDCCH signalincluding downlink assignment control information and the size of aPDCCH signal including uplink assignment control information are thesame, a terminal checks type information of assignment controlinformation, and by this means can distinguish between downlinkassignment control information and uplink assignment controlinformation. The PDCCH format to transmit uplink assignment controlinformation is PDCCH format 0, and the PDCCH format to transmit downlinkassignment control information, transmitted in a PDCCH signal of thesame size as for uplink assignment control information, is PDCCH format1A.

However, cases might occur where the information size of uplinkassignment control information determined from the uplink bandwidth(that is, the number of bits required for transmission) and theinformation size of downlink assignment control information determinedfrom the downlink bandwidth differ. To be more specific, if an uplinkbandwidth is small, the information size of uplink assignment controlinformation becomes small, and, if a downlink bandwidth is small, theinformation size of downlink assignment control information becomessmall. If a difference in bandwidth results in a difference in theinformation size like this, by adding zero information to the smallerassignment control information (that is, by performing zero-padding),the size of downlink assignment control information and the size ofuplink assignment control information are made equal. By this means,whether the content is downlink assignment control information or uplinkassignment control information, PDCCH signals have the same size.

The size adjustment of control information as mentioned above reducesthe number of times of blind detection at a terminal on the receivingside. However, when a downlink transmission bandwidth of a base stationis wide, a base station transmits many PDCCH signals at once, so that aterminal cannot reduce the number of times of blind detection much inits normal operation, and the increase of circuit scale causes aproblem.

Therefore, to reduce the number of times of blind detection on aterminal more, a terminal employs the method to limit a physical regionwhere a terminal receives control information. Thus, each terminal isreported in advance the time and frequency region that may includecontrol information for that terminal, and performs blind detection onlyin a terminal-specific region where control information for thatterminal is likely to be included. This terminal-specific physicalregion is called “dedicated region (EU SS: UE specific Search Space).”This dedicated region is associated with for example, terminal ID. Also,a time and frequency interleaving is employed to keep the effect of timediversity and frequency diversity at a certain level in the wholededicated region.

On the other hand, a PDCCH signal includes control information that isreported at once to a plurality of terminals (for example, schedulinginformation about downlink broadcast signal). To transmit this controlinformation, a physical region that is common to all terminals, called“common region (Common SS: Common Search Space),” is prepared in a PDCCHsignal.

A terminal requires both control information included in a dedicatedregion and control information included in a common region, so that aterminal needs to perform blind detection for all of uplink controlinformation and downlink control information included in a dedicatedregion and uplink control information and downlink control informationincluded in a common region.

Also, the standardization of 3GPP LTE-advanced has been started torealize much faster communication than 3GPP LTE. 3GPP LTE-advancedsystem (hereinafter referred to as “LTE-A system”) adheres 3GPP LTEsystem. (hereinafter referred to as “LTE system”). In 3GPP LTE-advanced,to realize a downlink transmission speed up to maximum 1 Gbps, a basestation and a terminal which can communicate in wideband frequency of 20MHz or more are expected to be introduced.

Also, in 3GPP LTE-Advanced, throughput requirements for an uplink and adownlink are different, so that communication bandwidths for an uplinkand a downlink may be made asymmetric. Specifically, in 3GPPLTE-Advanced, it is considered to make the communication bandwidth of adownlink wider than the communication bandwidth of an uplink.

Here, a base station to support LTE-A system (hereinafter referred to as“LTE-A base station”) is formed to be able to communicate using aplurality of “component bands.” “Component band” is a bandwidth formaximum 20 MHz here and is defined as the basic unit of communicationband. Furthermore, “component band” in a downlink (hereinafter referredto as “downlink component band”) is defined as a band separated bydownlink frequency bandwidth information in BCH broadcasted from a basestation, or a band defined by the range of distribution when a downlinkcontrol channel (PDCCH) is arranged in a distributed manner. Also,“component band” in an uplink (hereinafter referred to as “uplinkcomponent band”) is defined as a band separated by uplink frequencybandwidth information in BCH broadcasted from a base station, or thebasic unit of a communication band of 20 MHz or less including a PUSCH(Physical Uplink Shared CHannel) near the center, and a PUCCH (PhysicalUplink Control CHannel) for an LTE on both ends. Also, in 3GPPLTE-Advanced, “component band” may be designated as “ComponentCarrier(s)” in English.

FIG. 1 is a diagram showing an arrangement example of each channel in anLTE-A system where the communication bandwidth and the numbers ofcomponent bands of an uplink and a downlink are asymmetric. In FIG. 1,to let a terminal transmit an uplink signal, an LTE-A base stationreports assignment control information using PDCCH from both twodownlink component bands. Since an uplink component band is associatedwith both downlink component bands, regardless of the PDCCH whicheverdownlink component band is used, the PUSCH is transmitted in the sameuplink band. Also, downlink assignment control information may betransmitted from both two downlink component bands, and is used toindicate downlink assignment control information in a downlink componentband where each piece of downlink resource assignment information wastransmitted, to a terminal.

By receiving assignment control information in this way, an LTE-Aterminal can receive a plurality of component bands at the same time.However, an LTE terminal can receive only one component band at once. Togroup a plurality of component bands as an allocation band for singlecommunication is called “carrier aggregation (Carrier aggregation).”This carrier aggregation can improve throughput.

CITATION LIST Non Patent Literature NPL 1

3GPP TS 36.211 V8.4.0, “Physical Channels and Modulation (Release 8),”Sep. 2008

NPL 2

3GPP TS 36.212 V8.4.0, “Multiplexing and channel coding (Release 8),”Sep. 2008

NPL 3

3GPP TS 36.213 V8.4.0, “Physical layer procedures (Release 8),” Sep.2008

BRIEF SUMMARY Technical Problem

Meanwhile, in FIG. 1, the communication bandwidth of an LTE-A system is30 MHz in the downlink, and includes 20 MHz downlink component band in alow frequency side and 10 MHz downlink component band in a highfrequency side. On the other hand, an uplink is 20 MHz and includes oneuplink component band.

In FIG. 1, the bandwidths of a downlink component band and an uplinkcomponent band in low frequency side are equal, so that, as for thispair, the information size of uplink assignment control information anddownlink assignment control information is nearly the same. Thus,zero-padding is rarely performed. By contrast with this, since thebandwidths of a downlink component band and an uplink component band inhigh frequency side become larger, as for this pair, much zeroinformation is added to the smaller downlink assignment controlinformation until this downlink assignment control information sizebecomes equal to the uplink assignment control information size.However, zero-padding is performed for size adjustment, and zeroinformation itself carries no meaning. Thus, downlink assignment controlinformation includes fundamentally unnecessary signal, so that ifoverall power is fixed, power per information bit fundamentallynecessary declines.

Also, generally, downlink assignment control information is moresignificant than uplink assignment control information. That is,downlink assignment control information is used to report not onlyresource assignment information of a downlink data channel, but alsoscheduling information of other important information, such as paginginformation and broadcast information. Thus, it is preferable afrequency of zero-padding to downlink assignment control information todecrease.

Here, frequency diversity effect that a PDCCH can achieve depends on thebandwidth of a downlink component band. Thus, since in the downlinkcomponent band of a narrow bandwidth frequency diversity effect becomessmaller, a cause that will reduce quality should be removed as much aspossible. However, as for zero-padding, the narrower the bandwidth of adownlink component band is, the higher the possibility zero-padding isperformed.

This kind of situation cannot occur in an LTE system where no carrieraggregation concept exists since generally a downlink frequencybandwidth is larger than an uplink frequency bandwidth associated withthe downlink frequency bandwidth. On the other hand, in an LTE-A system,where carrier aggregation is introduced and where furthermore aplurality of downlink component bands are associated with one uplinkcomponent band, although a downlink frequency bandwidth is larger thanan uplink frequency bandwidth on the whole, as for the component band,the situation where a downlink component band is narrower than an uplinkcomponent band may occur frequently.

Also, to avoid zero-padding, a method of making the information sizes ofuplink assignment control information and downlink assignment controlinformation different is also possible. However, in this case, aterminal has to perform blind detection separately for two pieces ofassignment control information having different numbers of informationbits. Thus, the number of times of blind detection increases, and,accompanying this, the increase of circuit scale becomes a problem.

In view of the above, it is an object of the present invention toprovide a radio terminal, radio base station, channel signal formingmethod and channel signal receiving method, when communicating with anuplink component band and a plurality of downlink component bandsassociated with the uplink component band, by reducing the frequency toperform size adjustment processing for downlink assignment controlinformation to prevent the quality of downlink assignment controlinformation from being degrading.

Solution of Problem

A radio base station according to the present invention is a radio basestation that allocates component band groups on a per radio terminalbasis and that is able to communicate with radio terminals using acomponent band groups, each component band group being formed with anuplink component band and a plurality of downlink component bandsassociated with the uplink component band, and that employs aconfiguration having; a forming section that forms channel signals on aper downlink component band basis, each channel signal having a commonregion that is common between all radio terminals and a dedicated regionthat is allocated to an individual radio terminal on a dedicated basis,downlink assignment control information for an arbitrary target terminalbeing included in the common region and in the dedicated region, in allchannel signals to be transmitted in a downlink component band allocatedto the arbitrary target terminal, uplink assignment control informationfor the arbitrary target terminal being included in the dedicated regiononly in part of the channel signals, and included in the common regionat least in the part of the channel signals; and, an information sizeadjustment section that adjusts an information size of uplink controlinformation and downlink control information for the arbitrary targetterminal, included in the formed channel signals, based on a sizeadjustment reference, in all downlink component bands that are allocatedto the arbitrary target terminal, in the common region, a larger one ofa downlink assignment control information size determined from abandwidth of a downlink component band in which a channel signal havingthe common region is sent, and an uplink assignment control informationsize determined from a bandwidth of an uplink component band associatedwith the downlink component band, being used as a size adjustmentreference, in a dedicated region including uplink assignment controlinformation for the arbitrary target terminal, the larger one of thedownlink assignment control information size determined from thebandwidth of the downlink component band in which the channel signalhaving the dedicated region is sent, and the uplink assignment controlinformation size determined from the bandwidth of the uplink componentband associated with the downlink component band, being used as the sizeadjustment reference, in a dedicated region not including uplinkassignment control information for the arbitrary target terminal, thedownlink assignment control information size determined from thebandwidth of the downlink component band in which the channel signalhaving the dedicated region is sent, being used as the size adjustmentreference.

A radio terminal according to the present invention is a radio terminalthat is able to communicate with a radio base station using a componentband group that is allocated by the radio base station and that isformed with an uplink component band and a plurality of downlinkcomponent bands associated with the uplink component band, and thatincludes a radio receiving section that receives channel signals on aper downlink component band basis, each channel signal having a commonregion that is common between all radio terminals and a dedicated regionthat is allocated to an individual radio terminal on a dedicated basis,and including uplink assignment control information and downlinkassignment control information; a determining section that determines abasic information size to use in a receiving process of channel signalsof each downlink component band; and a channel signal receiving processsection that performs the receiving process of the channel signals basedon the basic information size, where in all downlink component bandsthat are allocated to the radio terminal, in the common region, thedetermining section determines the basic information size based on thelarger one of a downlink assignment control information size determinedfrom a bandwidth of a downlink component band in which a channel signalhaving the common region is sent, and an uplink assignment controlinformation size determined from a bandwidth of an uplink component bandassociated with the downlink component band; in a dedicated regionincluding uplink assignment control information for the radio terminal,the determining section determines the basic information size based onthe larger one of the downlink assignment control information sizedetermined from the bandwidth of the downlink component band in which achannel signal having the dedicated region is sent, and the uplinkassignment control information size determined from the bandwidth of theuplink component band associated with the downlink component band; andin a dedicated region not including uplink assignment controlinformation for the radio terminal, the determining section determinesthe basic information size based on the downlink assignment controlinformation size determined from the bandwidth of the downlink componentband in which the channel signal having the dedicated region is sent.

A channel signal forming method according to the present invention is achannel signal forming method that forms channel signals for a pluralityof downlink component bands associated with an uplink component band,and that includes the steps of: forming channel signals on a perdownlink component band basis, each channel signal having a commonregion that is common between all radio terminals and a dedicated regionthat is allocated to an individual radio terminal on a dedicated basis;and adjusting the information size of uplink assignment controlinformation and downlink assignment control information included in theformed channel signals, based on a size adjustment reference, wheredownlink assignment control information the arbitrary target terminalbeing included in the common region and the dedicated region in allchannel signal to be transmitted in the downlink component bandallocated to the arbitrary target terminal, uplink assignment controlinformation for the arbitrary target terminal being included in thededicated region only in part of the channel signals, and included inthe common region at least in the part of the channel signals; and inall downlink component bands that are allocated to the arbitrary targetterminal, in the common region, the larger one of the information sizeof downlink assignment control information determined from the bandwidthof the downlink component band in which the channel signal having thecommon region is sent, and the information size of uplink assignmentcontrol information determined from the bandwidth of the uplinkcomponent band associated with the downlink component band, being usedas the size adjustment reference, in the dedicated region including theuplink assignment control information for the arbitrary target terminal,the larger one of the information size of downlink assignment controlinformation determined from the bandwidth of the downlink component bandin which the channel signal having the dedicated region is sent, and theinformation size of uplink assignment control information determinedfrom the bandwidth of the uplink component band associated with thedownlink component band, being used as the size adjustment reference, inthe dedicated region not including the uplink assignment controlinformation to the arbitrary target terminal, the information size ofdownlink assignment control information determined from the bandwidth ofthe downlink component band in which the channel signal having thededicated region is sent, being used as the size adjustment reference.

A channel signal receiving method according to the present invention isa channel signal receiving method that receives channel signals for aplurality of downlink component bands associated with an uplinkcomponent band, and that includes the steps of: receiving channelsignals having a common region that is common between all radioterminals and a dedicated region that is allocated to an individualradio terminals on a dedicated basis, and including uplink assignmentcontrol information and downlink assignment control information;determining the basic information size to use in a receiving process ofthe channel signals of each downlink component band; and performing areceiving process of the channel signals based on the basic informationsize, wherein all downlink component bands that are allocated to theradio terminal, in the common region, the basic information size isdetermined based on the larger one of an information size of a downlinkassignment control information determined from a bandwidth of a downlinkcomponent band in which the channel signal having the common region issent, and an information size of uplink assignment control informationdetermined from a bandwidth of an uplink component band associated withthe downlink component band, in the dedicated region including theuplink assignment control information for the radio terminal, the basicinformation size is determined based on the larger one of theinformation size of downlink assignment control information determinedfrom the bandwidth of the downlink component band in which the channelsignal having the dedicated region is sent, and the information size ofuplink assignment control information determined from the bandwidth ofthe uplink component band associated with the downlink component band;and in the dedicated region not including uplink assignment controlinformation for the radio terminal, the basic information size isdetermined based on the information size of downlink assignment controlinformation determined from the bandwidth of the downlink component bandin which the channel signal having the dedicated region is sent.

Advantageous Effects of Invention

The present invention provides radio terminal, radio base station,channel signal forming method, and channel signal receiving method toprevent the quality of downlink assignment control information fromdegrading.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows an arrangement example of each channel in an LTE-A systemwhere the communication bandwidth (the number of component bands) isasymmetric between an uplink and a downlink;

FIG. 2 is a block diagram showing a configuration of a base stationaccording to Embodiment 1 of the present invention;

FIG. 3 is a block diagram showing a configuration of a terminalaccording to Embodiment 1 of the present invention;

FIG. 4 shows operations of a base station and a terminal;

FIG. 5 shows the method of determining size adjustment reference ofdownlink assignment control information;

FIG. 6 shows the method of determining size adjustment reference ofdownlink assignment control information;

FIG. 7 shows the method of determining size adjustment reference ofdownlink assignment control information;

FIG. 8 shows the method of determining size adjustment reference ofdownlink assignment control information;

FIG. 9 is a block diagram showing a configuration of a base stationaccording to Embodiment 2 of the present invention;

FIG. 10 is a block diagram showing a configuration of a terminalaccording to Embodiment 2 of the present invention; and

FIG. 11 shows operations of a base station and a terminal.

DETAILED DESCRIPTION

Now, embodiments of the present invention will be explained in detailwith reference to the accompanying drawings. Here, in embodiments, thesame components will be assigned the same reference numerals and theirexplanations will be omitted.

Embodiment 1

FIG. 2 is a block diagram showing a configuration of base station 100according to Embodiment 1 of the present invention. In FIG. 2, basestation 100 includes control section 101, PDCCH generating section 102,information size adjusting section 103, CRC (Cyclic Redundancy Check)adding section 104, modulating section 105 and 106, SCH/BCH generatingsection 107, multiplexing section 108, IFFT section 109, CP addingsection 110, RF transmission section 111, RF reception section 112, CPremoving section 113, FFT section 114, extracting section 115, IDFTsection 116, and data reception section 117. Base station 100 isconfigured to be able to communicate with terminal 200 (described later)using a component band group composed of an uplink component band and aplurality of downlink component bands associated with the uplinkcomponent band. A component band group is set for each terminal 200.Some or all of a plurality of component bands composing the componentband group allocated to first terminal 200 may overlap with aconstituent component band of the component band group allocated tosecond terminal 200.

Control section 101 generates control information (including uplinkassignment control information and downlink assignment controlinformation) and region assignment information indicating to which oneof a dedicated region or a common region each piece of controlinformation is allocated. This control information includes componentband group setting information individually set for each terminal 200,“basic component band information (Anchor Carrier)” (described later),dedicated assignment control information, such as resource assignmentinformation in component bands composing a component band group, andcommon assignment control information which is common to all terminals200. While dedicated region assignment control information is generatedfor control information to be allocated to each terminal 200 on adedicated basis, common region assignment information is generated forcommon control information that is common for all terminals 200.

Also, while downlink assignment control information for given terminal200 is allocated to all of a plurality of downlink component bandscomposing the component band group set for that terminal 200, controlsection 101 allocates uplink assignment control information for thatterminal 200 only to part of the plurality of downlink component bands.The allocation target downlink component band where uplink assignmentcontrol information is allocated is “basic component band,” andinformation related to this basic component band is the above mentioned“basic component band information.” This basic component bandinformation is reported to a given terminal in advance. If this basiccomponent band information is common between given terminals 200,information may be included in BCH in SCH/BCH generating section 107 andbroadcast.

To information size adjusting section 103, control section 101 outputsinformation size comparing information showing the difference in sizebetween the information size of downlink assignment control informationdetermined from the bandwidth of the basic component band and theinformation size of uplink assignment control information determinedfrom the bandwidth of the uplink component band associated with thedownlink component band.

PDCCH generating section 102 receives control information and regionassignment information generated in control section 101, and generates aPDCCH signal to be sent in each downlink component band, based on thesecontrol information and region assignment information.

Specifically, PDCCH generating section 102 generates a PDCCH signal asfollows. While including both uplink assignment control information anddownlink assignment control information in a PDCCH signal to be placedin a downlink component band indicated in basic component bandinformation, PDCCH generating section 102 only includes downlinkassignment control information in other downlink component bands. Thisprocess of sorting uplink assignment control information and downlinkassignment control information is performed based on basic componentband information. Also, while mapping common assignment controlinformation to a common region of a PDCCH signal, PDCCH generatingsection 102 maps dedicated assignment control information to a dedicatedregion. This process of sorting common assignment control informationand dedicated assignment control information is performed based onregion assignment information.

Information size adjusting section 103 receives control information andregion assignment information generated in control section 101. Based onthese control information and region assignment information, informationsite adjusting section 103 adjusts the information size of uplinkassignment control information and downlink assignment controlinformation included in a PDCCH signal received from PDCCH generatingsection 102.

Specifically, based on basic component band information, informationsize adjusting section 103 determines whether a PDCCH signal subject toinformation size adjustment is to be transmitted in the basic componentband or in a different downlink component band.

In a common region of the first PDCCH signal (that is a PDCCH signalwhich does not include uplink assignment information) which is sent in adownlink component band other than the basic component band, informationsize adjusting section 103 uses the larger one of the information sizeof downlink assignment control information determined from the bandwidthof the target downlink component band in which the first PDCCH signal issent, and the information size of uplink assignment control informationdetermined from the bandwidth of an uplink component band associatedwith the target downlink component band, as a size adjustment reference,and, based on this size adjustment reference, information size adjustingsection 103 adjusts the information size of downlink assignment controlinformation. Also, in a dedicated region of the first PDCCH signal,information size adjusting section 103 uses the information size ofdownlink assignment control information determined from the bandwidth ofthe target downlink component band in which the first PDCCH signal issent, as a size adjustment reference, and adjusts the information sizeof downlink assignment control information based on this size adjustmentreference.

On the other band, as for the second PDCCH signal (that is a PDCCHsignal includes both uplink assignment control information and downlinkassignment control information) sent in the basic component band,information size adjusting section 103 uses the larger one of theinformation size of downlink assignment control information determinedfrom the bandwidth of the target downlink component band in which thesecond PDCCH signal is sent, and the information size of uplinkassignment control information determined from the bandwidth of theuplink component band associated with the target downlink component bandas a size adjustment reference, and, based on this size adjustmentreference, information size adjusting section 103 adjusts theinformation size of uplink assignment control information and downlinkassignment control information.

To be more specific, information size adjusting section 103 includes apadding section (not shown) to adjust the information size of controlinformation by adding zero information to control information. As forthe second PDCCH signal, this padding section adds zero information tothe smaller one of the information size of downlink assignment controlinformation and the information size of uplink assignment controlinformation until the information size of downlink assignment controlinformation and the information size of uplink assignment controlinformation have equal information size. To which one of downlinkassignment control information and uplink assignment control informationzero information is added is decided based on information size comparinginformation.

Also, in a common region of the first PDCCH signal, the padding sectionadds zero information to downlink assignment control information, untilit becomes equal to the target information size determined from thelarger one of the information size of downlink assignment informationdetermined from the bandwidth of the target downlink component band inwhich the first PDCCH signal is sent, and the information size of uplinkassignment control information determined from the bandwidth of anuplink component band associated with the target downlink componentband. On the other hand, in a dedicated region of the first PDCCHdespite which is larger or smaller between the information size ofdownlink assignment control information determined from the bandwidth ofa target downlink component band and the information size of uplinkassignment control information determined from the bandwidth of anuplink component band associated with the downlink component band, thepadding section adds zero information to downlink assignment controlinformation, until it becomes equal to the target information sizedetermined from the information size of downlink assignment informationdetermined from the bandwidth of a downlink component band in the firstPDCCH signal is sent.

Even if the downlink component band of first terminal 200 and thedownlink component band of second terminal 200 overlap, the overlappeddownlink component band may be the basic component band for firstterminal 200 and may be a component band other than the basic componentband for second terminal 200.

In this case, while mapping uplink assignment control information anddownlink assignment control information to first terminal 200, the PDCCHsignal sent in the overlapped downlink component band maps only downlinkassignment control information to second terminal 200.

For this reason, the process of mapping uplink assignment controlinformation and downlink assignment control information in PDCCHgenerating section 102, and the process of information size adjustmentof uplink assignment control information and downlink assignment controlinformation in information size adjusting section 103 are performed foreach piece of assignment control information included in the targetPDCCH signal based on the reference applied to destination terminal 200.

CRC adding section 104 adds a CRC bit to the PDCCH signal subjected tosize adjustment in information size adjusting section 103, and thenmasks the CRC bit with the terminal ID. However, scheduling informationrelated to a broadcast signal which a plurality of terminals needs toreceive is masked by an ID that is set in common between a plurality ofterminals. Then, CRC adding section 104 outputs the masked PDCCH signalto modulating section 105.

Modulating section 105 modulates a PDCCH signal input from CRC addingsection 104, and outputs the modulated PDCCH signal to multiplexingsection 108.

Modulating section 106 modulates input transmission data (downlinkchannel data), and outputs a modulated transmission data signal tomultiplexing section 108.

SCH/BCH generating section 107 generates a SCH and a BCH, and outputsthe generated SCH and BCH to multiplexing section 108.

Multiplexing section 108 multiplexes the PDCCH signal input frommodulating section 105, the data signal (that, is a PDSCH signal) inputfrom modulating section 106, and the SCH and BCH input from SCH/BCHgenerating section 107. Based on the terminal ID input from controlsection 101 and downlink assignment control information associated withthe terminal ID, multiplexing section 108 maps a data signal (a PDSCHsignal) for terminal 200 associated with the terminal ID, to a downlinkcomponent band.

Also, multiplexing section 108 maps the PDCCH signal input frommodulating section 105, to the dedicated resource region and the commonresource region in the resource region allocated for a PDCCH.Specifically, the PDCCH signal associated with a data signal which onlya certain terminal should receive, is mapped to the resource associatedwith the terminal ID of the target terminal in the dedicated resourceregion, and the PDCCH signal associated with a data signal which aplurality of terminals should receive at once, is mapped to the resourcein the common resource region.

IFFT section 109 converts a multiplex signal into a time waveform, andCP adding section 110 acquires an OFDM signal by adding a CP to thistime waveform.

RF transmission section 111 performs a radio transmission process (suchas up-conversion and a digital-to-analog (D/A) conversion) to an OFDMsignal input from CP adding section 110, and transmits the resultthrough an antenna. Then, an OFDM signal including assignment controlinformation is sent.

RF reception section 112 performs a radio receiving process (such as adown-conversion and an analog-to-digital (A/D) conversion) to a receivedsignal which is received in a receiving band through an antenna, andoutputs the received signal to CP removing section 113.

CP removing section 113 removes the CP from a received signal, and FFTsection 114 converts a received signal, from which the CP is removed,into a frequency domain signal.

Based on uplink assignment control information input from controlsection 101, extracting section 115 extracts uplink channel data from afrequency domain signal input from FFT section 114, and IDFT (InverseDiscrete Fourier Transform) section 116 converts the extracted signalinto a time domain signal and outputs the time domain signal to datareception section 117.

Data reception section 117 decodes the time domain signal input fromIDFT section 116. And data reception section 117 outputs decoded uplinkchannel data as received data.

FIG. 3 is a block diagram showing the configuration of terminal 200according to Embodiment 1 of the present invention. In FIG. 3, terminal200 includes RF reception section 201, CP removing section 202, FFTsection 203, frame synchronization section 204, demultiplexing section205, broadcast signal reception section 206, information sizedetermination section 207, PDCCH reception section 208, formatdetermination section 209, PDSCH reception section 210, modulatingsection 211, DFT section 212, frequency mapping section 213, IFFTsection 214, CP adding section 215, and RF transmission section 216.

RF reception section 201 performs a radio receiving process (such as adown-conversion and an analog-to-digital (A/D) conversion) to a receivedsignal (in this case, an OFDM signal) which is received in a receivingband through an antenna, and outputs the received signal to CP (CyclicPrefix) removing section 202.

CP removing section 202 removes the CP from a received signal, and FFT(Fast Fourier Transform) section 203 converts a received signal, fromwhich the CP is removed, into a frequency domain signal. This frequencydomain signal is output to frame synchronization section 204.

While searching a SCH included in a signal input from FFT section 203,frame synchronization section 204 establishes synchronization (framesynchronization) with base station 100. Also, frame synchronizationsection 204 acquires the cell ID associated with the sequence used for aSCH (a SCH sequence). That is, the same process as a normal cell searchis performed in frame synchronization section 204. Frame synchronizationsection 204 outputs frame synchronization timing information to show aframe synchronization timing, and the signal input from FFT section 203to demultiplexing section 205.

Based on frame synchronization timing information input from framesynchronization section 204, demultiplexing section 205 demultiplexesthe signal input from frame synchronization section 204 into a broadcastsignal (that is, a BCH), a control signal (that is, a PDCCH signal), anda data signal (that is, a PDSCH signal). Demultiplexing section 205receives information related to a downlink component band from broadcastsignal reception section 206, and based on this information, extracts aPDCCH signal on a per downlink component band basis.

Broadcast signal reception section 206 reads the contents of a BCH inputfrom demultiplexing section 205, and acquires information related to theconfiguration of the downlink band and uplink band of base station 100.Broadcast signal reception section 206 acquires, for example, the numberof uplink component bands, the number of downlink component bands, theidentification number and bandwidth of each component band, informationassociated an uplink component band with a downlink component band, andbasic component band information. Broadcast signal reception section 206outputs acquired BCH information to information size determinationsection 207, PDCCH reception section 208, and format determinationsection 209.

Information size determination section 207 receives a PDCCH signal fromdemultiplexing section 205, and determines the basic information size toperform blind detection on this PDCCH signal. This basic informationsize is determined based on basic component band information, which isreceived from broadcast signal reception section 206, and the bandwidthof each component band.

Specifically, in a common region of a PDCCH signal of a downlinkcomponent band other than the basic component band (that is, a commonregion of a PDCCH signal of a component band which does not includeuplink assignment information for terminal 200), information sizedetermination section 207 uses the larger one of the information size ofdownlink assignment control information determined from the bandwidth ofa downlink component band in which the PDCCH signal is sent, and theinformation size of uplink assignment control information determinedfrom the bandwidth of an uplink component band associated with thetarget downlink component band, as information size reference, and, in adedicated region, decides the basic information size based on theinformation size of downlink assignment control information determinedfrom the bandwidth of the target downlink component band.

Also, as for a PDCCH signal of the basic component band (that is, aPDCCH signal of a component band includes both uplink assignmentinformation for terminal 200 and downlink assignment information),information size determination section 207 uses the larger one of theinformation size of downlink assignment control information determinedfrom the bandwidth of a target downlink component band in which thePDCCH signal is sent, and the information size of uplink assignmentcontrol information determined from the bandwidth of an uplink componentband associated with the target downlink component band as informationsize reference.

Information size determination section 207 outputs information relatedto the determined basic information size, and the PDCCH signalassociated with this information to PDCCH reception section 208.

PDCCH reception section 208 performs blind detection for a PDCCH signalbased on the basic information size decided in information sizedetermination section 207.

That is, PDCCH reception section 208 specifies the CRC bit part usingthe basic information size (payload size) decided in information sizedetermination section 207. Next, after demasking the specified CRC bitpart using the terminal ID of terminal 200 in a dedicated region, PDCCHreception section 208 decides the PDCCH signal as a PDCCH signaltransmitted for terminal 200, if the CRC calculation result is “OK” withrespect to the whole PDCCH signal. However, since in a common regionthere is a possibility that both assignment information for terminal 200and assignment information to be received by a plurality of terminals(for example, broadcast signal scheduling information) may be sent, in acommon region, PDCCH reception section 208 performs both demaskingprocess by the terminal ID of terminal 200 and demasking process by anID set in common between a plurality of terminals, and executes the CRCcalculation. Thus, the PDCCH signal that is decided to be received byterminal 200 is output to format determination section 209.

Based on type information of assignment control information included ina PDCCH signal received from PDCCH reception section 208, formatdetermination section 209 decides whether the format of the PDCCH signalis format 0 or format 1A. When determining on format 0, formatdetermination section 209 outputs uplink assignment control informationincluded in the PDCCH signal, to frequency mapping section 213.

Also, when determining on format 1A, format determination section 209outputs downlink assignment control information included in the PDCCHsignal, to PDSCH reception section 210.

Based on downlink assignment control information input from formatdetermination section 209, PDSCH reception section 210 extracts receiveddata from the PDSCH signal input from demultiplexing section 205.

Modulating section 211 modulates transmission data and outputs aresulting modulated signal to DFT (Discrete Fourier Transform) section212.

DFT section 212 converts a modulated signal, which is input frommodulating section 211, into a frequency domain, and outputs a resultingplurality of frequency components to frequency mapping section 213.

In accordance with uplink assignment control information input fromformat determination section 209, frequency mapping section 213 maps aplurality of frequency components input from DFT section 212, on a PUSCHplaced in an uplink component band.

IFFT section 214 converts a mapped plurality of frequency componentsinto a time domain waveform, and CP adding section 215 adds a CP to thetime domain waveform.

RF transmission section 216 performs a radio transmission process (suchas an up-conversion and a digital-to-analog (D/A) conversion) to a CPadded signal, and transmits it through an antenna.

Next, an operation of base station 100 and terminal 200, which has theabove mentioned configuration, is described. FIG. 4 is a view forexplaining an operation of base station 100 and terminal 200.

In FIG. 4, one uplink component band UB1 is associated with two downlinkcomponent bands DB1 and DB2 as a component band group for first terminal200. In FIG. 4, the bandwidth of UB1 and DB1 are 20 MHz and thebandwidth of DB2 is 10 MHz. DB1 is defined as a basic component band forfirst terminal 200 here.

Base station 100 determines uplink component band UB1 as uplink channelresource to first terminal 200, and downlink component bands DB1 and DB2as downlink channel resource.

Then, base station 100 includes uplink assignment control informationand downlink assignment control information into the PDCCH signal, andtransmits them to terminal 200.

However, base station 100 does not transmit uplink assignment controlinformation for first terminal 200 in all downlink component bandsallocated to first terminal 200, and base station 100 transmits uplinkassignment control information only in part of the downlink componentbands. On the other hand, base station 100 transmits downlink resourceassignment information in all downlink component bands allocated tofirst terminal 200.

In the case of FIG. 4, since DB1 is the basic component band for a firstterminal 200, a PDCCH signal to be sent in DB1 includes both uplinkassignment control information and downlink assignment controlinformation. On the other hand, a PDCCH signal to be sent in DB2includes downlink assignment control information only. The arrow from aPDCCH towards uplink data (UL Data) shows that uplink assignment controlinformation is sent in the PDCCH. Also, the arrow from a PDCCH towardsdownlink data (DL Data) or towards a D-BCH shows that downlinkassignment control information is sent in the PDCCH.

Also, the information size of a PDCCH signal is adjusted if necessary.In information size adjusting section 103, this information sizeadjustment is performed for a PDCCH signal (that is, a PDCCH signal ofthe basic component band) of a component band including both uplinkassignment control information and downlink assignment controlinformation, and for downlink assignment control information included ina common region of a PDCCH signal sent in a band other than a basiccomponent band. Specifically, as for a basic component band, informationsize adjusting section 103 adds zero information to the smaller one ofthe information size of downlink assignment control information and theinformation size of uplink assignment control information until theinformation size of downlink assignment control information and theinformation size of uplink assignment control information have equalinformation size. Also, as for downlink assignment control informationincluded in a common region of the PDCCH signal sent with a downlinkcomponent band other than the basic component band, information sizeadjusting section 103 uses the larger one of the information size ofdownlink assignment control information determined from the bandwidth ofa downlink component band in which the first PDCCH signal is sent, andthe information size of uplink assignment control information determinedfrom the bandwidth of an uplink component band associated with thetarget downlink component band as a size adjustment reference, and,adjusts the information size.

On the other hand, the size of downlink assignment control informationincluded in a dedicated region of a PDCCH signal sent by component bandother than a basic component band is decided only from the bandwidth ofa downlink component band which sends downlink assignment controlinformation.

Here, the method of determining size adjustment reference of downlinkassignment control information will be described in detail.

FIG. 5 through FIG. 8 is a diagram showing the method of determiningsize adjustment reference of downlink assignment control information.

At first, a case will be described where a component band group shown inFIG. 5 is allocated to first through third terminal 200 (in FIG. 6,shown as UE A, UE B, and UE C). In FIG. 5, a component band group iscomposed of a downlink component band (band A) of a 20 MHz bandwidth, adownlink component band (band B) of a 10 MHz bandwidth, and an uplinkcomponent band of a 15 MHz bandwidth.

FIG. 6 shows a component band type for each band (that is, informationillustrates whether a basic component band (a band where uplinkassignment control information (UL grant) is sent) or a component bandother than the basic component band) and size adjustment reference ineach bandwidth of a dedicated region and a common region for each UE.

As shown in FIG. 6, band A is a basic component band for UE A. Also,band B is a basic component band for UE B. Also, both band A and B are abasic component band for UE C.

What has to be focused on here is the size adjustment reference in adedicated region in band B for UE A. As mentioned above, in a dedicatedregion of the downlink component band other than a basic component band,despite which is larger or smaller between the information size ofdownlink assignment control information determined from the bandwidth ofa target downlink component band and the information size of uplinkassignment control information determined from the bandwidth of anuplink component band associated with the downlink component band, theinformation size of downlink assignment control information determinedfrom the bandwidth of a target downlink component band is used as a sizeadjustment reference. That is, unlike a basic component band, whichalways uses the larger one of the information size of uplink assignmentcontrol information and downlink assignment control informationdetermined from the bandwidth, as a size adjustment reference, in adedicated region of a downlink component band other than a basiccomponent band, even if the information size of downlink assignmentcontrol information determined from a downlink bandwidth is smaller thanthe information size of uplink assignment control information determinedfrom an uplink component bandwidth, the information size of downlinkassignment control information determined from the bandwidth of adownlink component band, is used as a size adjustment reference. In thiscase, it is not necessary to perform size adjustment by zero padding todownlink assignment control information, it is possible to prevent thequality of downlink assignment control information from beingdeteriorated.

On the other hand, in a common region, it is required to use the largerone of the information size of downlink assignment control informationdetermined from the bandwidth of a downlink component band and theinformation size of uplink assignment control information determinedfrom the bandwidth of an uplink component band associated with thetarget downlink component band, as a size adjustment reference. This isbecause a case might occur where a downlink component band is not thebasic component for one terminal 200 but is the basic component band foranother terminal 200, and, in a common region, a control signal,associated with a downlink data signal to be received by a plurality ofterminals at once, is transmitted. Thus, considering a certain terminal200 alone, in a common region of a downlink component band other than abasic component band, as in a dedicated region, the information size ofdownlink assignment control information determined from the bandwidth ofa downlink component band can be used as a size adjustment reference.However, since it is a basic component band for another terminal 200, inthis basic downlink component band, uplink assignment controlinformation, which is necessary for other terminal 200, may betransmitted in addition to a control signal associated with a datasignal, which a plurality of terminals should receive at once. Thus, tolet all terminals 200 successfully receive a control signal associatedwith a downlink signal which should be received at once, and to let allterminals 200 successfully receive uplink assignment controlinformation, in a common region, the same selection reference of sizeadjustment reference as a basic component band is used, that the largerone of the information size of uplink assignment control information andthe information size of downlink assignment control informationdetermined from the bandwidth is used as a size adjustment reference.

Next, a case will be described where a component band group shown inFIG. 7 is allocated to first through third terminal 200 (in FIG. 8,shown as UE A, UE B, and UE C). In FIG. 7, a component band group iscomposed of a downlink component band (band A) of a 15 MHz bandwidth, adownlink component band (band B) of a 10 MHz bandwidth, and an uplinkcomponent band of a 20 MHz bandwidth.

FIG. 8 shows for each UE a component band type of each band and a sizeadjustment reference in a dedicated region and a common region of eachband.

What has to be focused on here is the size adjustment reference in adedicated region of band B for UE A and in a dedicated region of band Afor UE B. That is, in a dedicated region of a downlink component bandother than a basic component band, the information size of downlinkassignment control information determined from the bandwidth of adownlink component band, is used as a size adjustment reference, so thata component band group shown in FIG. 7 always uses not the informationsize of uplink assignment control information determined from an uplinkcomponent band, but the information size of downlink assignment controlinformation determined from the bandwidth of a downlink component bandhaving narrow bandwidth. In this case, it is not necessary to performsize adjustment by zero padding to downlink assignment controlinformation, it is possible to prevent the quality of downlinkassignment control information from being deteriorated.

A PDCCH signal, mapping process of assignment control information andinformation size adjustment process are performed as mentioned above,are received by terminal 200.

In terminal 200, information size determination section 207 decides abasic information size onto performing a blind detection on a receivedPDCCH signal. This basic information size is determined based on basiccomponent band information received from broadcast signal receptionsection 206, and the bandwidth of each component band.

Specifically, in a common region of a PDCCH signal of a downlinkcomponent band other than the basic component band (that is, a commonregion of a PDCCH signal which does not include uplink assignmentinformation for terminal 200), information size determination section207 uses the larger one of the information size of downlink assignmentcontrol information determined from the bandwidth of a target downlinkcomponent band in which the PDCCH signal is sent, and the informationsize of uplink assignment control information determined from thebandwidth of an uplink component band associated with the targetdownlink component band as a size adjustment reference, and, on theother hand, in a dedicated region, decides the basic information sizebased on the information size of downlink assignment control informationdetermined from the bandwidth of the target downlink component band.

Also, as for a PDCCH signal of the basic component band (that is, aPDCCH signal includes both uplink assignment information and downlinkassignment information for terminal 200), information size determinationsection 207 uses the larger one of the information size of downlinkassignment control information determined from the bandwidth of a targetdownlink component band in which the PDCCH signal is sent, and theinformation size of uplink assignment control information determinedfrom the bandwidth of an uplink component band associated with thetarget downlink component band as a size adjustment reference.

Then, PDCCH reception section 208 performs blind detection on a PDCCHsignal based on a basic information size determined by information sizedetermination section 207.

That is, PDCCH reception section 208 specifies the CRC bit part includedin a PDCCH signal according to a basic information size. Although thedifference between basic information sizes makes locations of CRC bitparts in PDCCH signals different, PDCCH reception section 208 canspecify a CRC bit part of a PDCCH signal sent from each region, byreceiving information of a basic information size in a dedicated regionand a common region of each downlink component band determined ininformation size determination section 207.

Next, after demasking the specified CRC bit part determined by theterminal ID of terminal 200 or by a common ID among a plurality ofterminals, PDCCH reception section 208 decides the PDCCH signal as aPDCCH signal transmitted for terminal 200 if CRC calculation result is“OK” with respect to the whole PDCCH signal.

Also, based on type information of resource assignment informationincluded in a PDCCH signal received from PDCCH reception section 208,format determination section 209 decides whether the format of the PDCCHsignal is format 0 or format 1A.

According to the above explanation, a PDCCH signal received in adedicated region of a downlink component band other than a basiccomponent band is always a downlink allocation signal, so that the typeinformation of resource assignment information is always supposed toindicate downlink assignment control information. That is, the partsassociated with the type information of resource assignment informationcan be used like a parity bit, or can be used to transmit other kinds ofinformation.

Although in the above description it has been shown that base station100 reports basic component band information to terminal 200 separately,but, when the uplink component band and downlink component band are notsymmetric, for example, the technical specification can define that thedownlink component band having low frequency as “basic component band.”That is, the method of reporting “basic component band” is not limitedspecifically.

Although in the above description it has been shown that the number ofuplink component bands and the number of downlink component bands that abase station supports are not symmetric, the present embodiment is notlimited to this. That is, even if the number of uplink component bandsand the number of downlink component bands that a base station supportsare symmetric, the present embodiment can be applied if the number ofcomponent bands allocated to each terminal (that is, instructed by abase station to receive) is asymmetric in the uplink and downlink.

The present embodiment limits allocating a PDCCH signal including uplinkassignment control information to part of downlink component band, andby this means reduces the possibility of performing zero padding todownlink assignment control information that is higher significance.

Also, a PDCCH signal of a downlink component band other than the basiccomponent band includes downlink resource assignment information alone.Then, in a dedicated region of the downlink component band other thanthe basic component band, the information size of downlink assignmentcontrol information determined from the bandwidth of a downlinkcomponent band is always used as a size adjustment reference, so thatthere is no need to perform information size adjustment. It is notnecessary to perform zero padding to downlink assignment controlinformation, it is possible to prevent the quality of downlinkassignment control information from being deteriorated. Similarly, asfor uplink assignment control information, the number and frequency ofpadding can be minimized.

However, in a common region of a downlink component band other than thebasic component band, the larger one of the information size of downlinkassignment control information determined from the bandwidth of adownlink component band and the information size of uplink assignmentcontrol information determined from the bandwidth of an uplink componentband associated with the target downlink component band, is used as asize adjustment reference. Therefore, even if different basic componentbands are applied to each terminal 200, terminal 200 on the receivingside can transmit downlink assignment control information withoutproblem.

According to the above explanation, in a downlink component band otherthan the basic component band, neither a dedicated region nor a commonregion transmits uplink assignment control information to given terminal200. However, the present invention is not limited to this, and it isequally possible to transmit uplink assignment control information in acommon region, even in a downlink component band other than the basiccomponent band. Therefore, in a common region, the selection referenceof a size adjustment reference is the same as the selection reference ofthe basic component band, so that as in the basic component band, it ispossible to match the information size between uplink assignment controlinformation and downlink assignment control information. By this means,it is possible to enhance flexibility of the scheduler in base station100 without increasing the number of blind detection in terminal 200.

That is, PDCCH generating section 102 includes downlink assignmentcontrol information for given terminal 200, in a common region and adedicated region of all channel signals to be sent in a downlink bandallocated to target terminal 200, includes uplink assignment controlinformation to be sent to arbitrary terminal 200, and on the other handincludes only to some part of the channel signal in a dedicated region,to at least part of the channel signal in a common region. In a commonregion of all channel signals of a downlink component band allocated totarget terminal 200, information size adjusting section 103 uses thelarger one of the information size of downlink assignment controlinformation determined from the bandwidth of a downlink component bandwhere the channel signal having the target common region is transmitted,and the information size of uplink assignment control informationdetermined from the bandwidth of an uplink component band associatedwith the target downlink component band, as a size adjustment reference.In a dedicated region including uplink allocated control information fortarget terminal 200, information size adjusting section 103 uses thelarger one of the information size of downlink assignment controlinformation determined from the bandwidth of a downlink component bandin which a channel signal having a dedicated region is sent, and theinformation size of uplink assignment control information determinedfrom the bandwidth of an uplink component band associated with thetarget downlink component band, as a reference of size adjustment. In adedicated region which does not include uplink allocated controlinformation for target terminal 200, information size adjusting section103 uses the information size of downlink assignment control informationdetermined from the bandwidth of a downlink component band in which achannel signal having a dedicated region is sent, as a size adjustmentreference.

Embodiment 2

As Embodiment 1, the present embodiment explains the configuration, whenthe communication bandwidth (the number of basic component band) isasymmetric between an uplink and a downlink, in a common region, anLTE-A system specific broadcast information (D-BCH+) (that is, an LTEterminal does not need to receive) and broadcast information of an LTEsystem (D-BCH) are transmitted one after another by time division.

FIG. 9 is a block diagram showing the configuration of base station 300of Embodiment 2 of the present invention. Compared to base station 100of Embodiment 1 shown in FIG. 2, base station 300 shown in FIG. 9 addsBCH+ generating section 318 and includes control section 301 instead ofcontrol section 101, information size adjusting section 303 instead ofinformation size adjusting section 103, and multiplexing section 308instead of multiplexing section 108. Parts in FIG. 9 that are the sameas in FIG. 2 will be assigned the same reference numerals as in FIG. 2and overlapping descriptions will be omitted.

As control section 101, control section 301 generates controlinformation (including uplink assignment control information anddownlink assignment control information), region assignment informationshowing each pieces of control information indicating whether eachcontrol information should be allocated to a dedicated region or acommon region, and BCH/BCH+ timing information. Also, controlinformation and region assignment information include the sameinformation as in Embodiment 1.

Also, control section 301 allocates downlink assignment controlinformation for given terminal 400 to all of a plurality of downlinkcomponent bands that form a component band group set for this terminal400, and on the other hand, allocates uplink assignment controlinformation for given terminal 400 only to part of the plurality ofdownlink component bands. Here, as Embodiment 1, an allocation targetdownlink component band where uplink assignment control information isallocated is “basic component band,” and information related to thisbasic component band is above mentioned “basic component bandinformation.”

Also, control section 301 outputs information size comparinginformation, showing the difference between the information size ofdownlink assignment control information determined from the bandwidth ofa basic component band, and the information size of uplink assignmentcontrol information determined from the bandwidth of an uplink componentband associated with the downlink component band, and BCH/BCH+ timinginformation, to information size adjusting section 303 and multiplexingsection 308. Also, BCH/BCH+ timing information is shared with allterminals 400 in advance.

As Embodiment 1, control section 301 outputs generated controlinformation and region assignment information to PDCCH generatingsection 102, outputs uplink assignment control information to extractingsection 115, and outputs terminal ID and common ID to CRC adding section104.

Information size adjusting section 303 receives control informationgenerated in control section 301, region assignment information, andBCH/BCH+ timing information. Based on these control information, regionassignment information, and BCH/BCH+ timing information, informationsize adjusting section 303 adjusts the information size of uplinkassignment control information and downlink assignment controlinformation included in a PDCCH signal received from PDCCH generatingsection 102.

Specifically, based on basic component band information, informationsize adjusting section 303 determines whether a PDCCH signal subject toinformation size adjustment should be transmitted in the basic componentband or in a different downlink component band.

Then, as for a common region of the first PDCCH signal (that is, a PDCCHsignal which does not include uplink assignment information) to be sentin a downlink component band other than the basic component band, in thesubframe where a BCH for an LTE terminal should be transmitted in adownlink component band other than the basic component band, informationsize adjusting section 303 uses the larger one of the information sizeof downlink assignment control information determined from the bandwidthof a downlink component band in which the first PDCCH signal is sent,and the information size of uplink assignment control informationdetermined from the bandwidth of an uplink component band associatedwith the target downlink component band as information size adjustment,and, based on this size adjustment reference, adjusts the informationsize of downlink assignment control information. Also, as for a commonregion of the first PDCCH signal, in the subframe where a BCH+ for anLTE-A terminal should be transmitted in a downlink component band otherthan the basic component band, information size adjusting section 303uses the information size of downlink assignment control informationdetermined from the bandwidth of a target downlink component band inwhich the first PDCCH signal is sent, and based on this size adjustmentreference, adjusts the information size of downlink assignment controlinformation.

Also, in a dedicated region of the first PDCCH signal, information sizeadjusting section 303 uses the information size of downlink assignmentcontrol information determined from the bandwidth of a target downlinkcomponent band in which the first PDCCH signal is sent, as a sizeadjustment reference, and based on this size adjustment reference,adjusts the information size of downlink assignment control information.

On the other hand, as for the second PDCCH signal (that is a PDCCHsignal includes both uplink assignment control information and downlinkassignment control information) to be sent in the basic component band,information size adjusting section 303 uses the larger one of theinformation size of downlink assignment control information determinedfrom the bandwidth of a downlink component band in which the secondPDCCH signal is sent, and the information size of uplink assignmentcontrol information determined from the bandwidth of an uplink componentband associated with the target downlink component band as sizeadjustment reference, and, based on this size adjustment reference,adjusts the information size of uplink assignment control informationand downlink assignment control information.

To be more specific, as in Embodiment 1, information size adjustingsection 303 includes a padding section (not shown) to adjust theinformation size of control information by adding zero information tocontrol information.

BCH+ generating section 318 generates BCH+ being broadcast informationfor an LTE-A terminal, and outputs generated BCH+ to multiplexingsection 308.

Multiplexing section 308 multiplexes the PDCCH signal input frommodulating section 105, the data signal (that is, a PDSCH signal) inputfrom modulating section 106, the SCH and BCH input from SCH/BCHgenerating section 107, and BCH+ input from BCH+ generating section 318.Based on the terminal ID input from control section 301 and downlinkassignment control information associated with the terminal ID,multiplexing section 308 maps a data signal (a PDSCH signal) forterminal 400 associated with the terminal ID, to a downlink componentband.

Also, multiplexing section 308 maps the PDCCH signal input frommodulating section 105, to the dedicated resource region and the commonresource region in the resource region allocated for a PDCCH.Specifically, the PDCCH signal associated with a data signal which onlya certain terminal should receive, is mapped to the resource associatedwith the terminal ID of the target terminal in a dedicated resourceregion, and the PDCCH signal associated with a data signal which aplurality of terminals should receive at once, is mapped to the resourcein the common resource region.

Also, based on BCH/BCH+ timing information input from control section301, multiplexing section 308 multiplexes BCH with PDSCH and PDCCH atthe timing BCH should be transmitted, and multiplexes BCH+ with PDSCHand PDCCH at the timing BCH+should be transmitted. That is, BCH and BCH+are multiplexed by time division.

FIG. 10 is a block diagram showing the configuration of terminal 400according to Embodiment 2 of the present invention. Compared to terminal200 of Embodiment 1 shown in FIG. 3, terminal 400 shown in FIG. 10includes demultiplexing section 405 instead of demultiplexing section205, broadcast signal reception section 406 instead of broadcast signalreception section 206, and information size determination section 407instead of information size determination section 207. Also, parts inFIG. 10 that are the same as in FIG. 3 will be assigned the samereference numerals as in FIG. 3 and overlapping descriptions will beomitted.

Based on frame synchronization timing information input from framesynchronization section 204, demultiplexing section 405 demultiplexesthe signal input from frame synchronization section 204 into broadcastsignal (that is, a BCH and a BCH+), a control signal (that is, a PDCCHsignal), and a data signal (that is, a PDSCH signal). Demultiplexingsection 405 receives information related to a downlink component bandfrom broadcast signal reception section 406, and based on thisinformation, extracts PDCCH signals on a per downlink component bandbasis. Also, demultiplexing section 405 holds BCH/BCH+ timinginformation which is shared between all terminals 400 in advance bymeans of reporting from base station 300, and demultiplexes BCH and BCH+from a signal input from frame synchronization section 204 based on thistiming information.

Broadcast signal reception section 406 reads the contents of BCH andBCH+ input from demultiplexing section 405, and as Embodiment 1 receivesinformation related to the configuration of the downlink band and uplinkband of base station 300. Broadcast signal reception section 406acquires, for example, the number of uplink component bands, the numberof downlink component bands, the identification number and bandwidth ofeach component band, information associated an uplink component bandwith a downlink component band, and basic component band information.Broadcast signal reception section 406 outputs acquired BCH and BCH+information to information size determination section 407, PDCCHreception section 208, and format determination section 209.

Information size determination section 407 receives a PDCCH signal andBCH/BCH+ timing information from demultiplexing section 405, anddetermines the basic information size to perform blind detection on thisPDCCH signal. This basic information size is determined based on basiccomponent band information, which is received from broadcast signalreception section 406, the bandwidth of each component band, andBCH/BCH+ timing information.

Specifically, as for a common region of a PDCCH signal of a downlinkcomponent band other than the basic component band (that is a commonregion of a PDCCH signal of a component band which does not includeuplink assignment information for terminal 200), in the subframe where aBCH for an LTE terminal should be transmitted in the target downlinkcomponent band, information size determination section 407 uses thelarger one of the information size of downlink assignment controlinformation determined from the bandwidth of a downlink component bandin which the PDCCH signal is sent, and the information size of uplinkassignment control information determined from the bandwidth of anuplink component band associated with the target downlink componentband, as size adjustment reference, and, as for a common region of aPDCCH signal of a downlink component band other than the basic componentband, in the subframe where a BCH+ for an LTE-A terminal should betransmitted in the target downlink component band, decides the basicinformation size based on the information size of downlink assignmentcontrol information determined from the bandwidth of the target downlinkcomponent band.

Also, in a dedicated region of a PDCCH signal of a downlink componentband other than the basic component band, information size determinationsection 407 decides the basic information size based on the informationsize of downlink assignment control information decided from thebandwidth of the target downlink component band.

Also, as for a PDCCH signal of the basic component band (that is, aPDCCH signal includes both uplink assignment information and downlinkassignment information for terminal 200), information size determinationsection 407 uses the larger one of the information size of downlinkassignment control information determined from the bandwidth of a targetdownlink component band in which the PDCCH signal is sent, and theinformation size of uplink assignment control information determinedfrom the bandwidth of an uplink component band associated with thetarget downlink component band as a size adjustment reference.

Information size determination section 407 outputs information about thedecided basic information size and the PDCCH signal associated with thisinformation to PDCCH reception section 208.

Next, operation of base station 300 and terminal 400 employing the abovementioned configuration will be explained with reference of FIG. 4 andFIG. 10. FIG. 4 is a conceptual diagram showing the timing a BCH for anLTE terminal is transmitted in the right downlink component band of basestation 300, and FIG. 11 is a conceptual diagram of a control signal atthe timing a BCH+ for an LTE-A terminal is transmitted in the rightdownlink component band of base station 300.

Differences between FIG. 11 and FIG. 4 include whether schedulinginformation of (D−) BCH will be transmitted in Format 1A, in whichtransmission uses a PDCCH in a common region, or whether schedulinginformation of (D−) BCH+ will be transmitted, and the difference betweenthe sizes of Format 1A. That is, FIG. 4 shows the first subframe where(D−) BCH scheduling information is transmitted, FIG. 11 shows the secondsubframe where (D−) BCH+ scheduling information is transmitted. Asmentioned above, as for a common region of a PDCCH signal of a downlinkcomponent band other than the basic component band, in the subframewhere a BCH+ for an LTE-A terminal should be transmitted in the targetdownlink component band, base station 300 and terminal 400 determine thebasic information size based on the information size of downlinkassignment control information determined from the bandwidth of a targetdownlink component band, and, by this means, even if the uplinkbandwidth is wider than the bandwidth of a target downlink componentband, do not perform a padding for Formal 1A. Therefore, in a commonregion, it is possible to avoid unnecessary padding for Format 1A.However, at the point when a BCH for an LTE is transmitted in the targetdownlink component band, to perform the same padding process as for anLTE terminal, backward compatibility can be kept.

Embodiments of the present invention have been described above.

Also, with the above embodiments, the relationship between a downlinkcomponent band and an uplink component band has been reported by a BCHfrom a base station. However, until a terminal receives (part of BCHs) aBCH showing the relationship with an uplink component band, a terminalcannot calculate the information size of Format 1A that should bedetermined by taking into account both the bandwidth of a downlinkcomponent band and the bandwidth of an uplink component band. For thisreason, when the bandwidth of an uplink component band is unknown on theterminal side, the information size of Format 1A will be calculated onthe premise that the bandwidth of the known downlink component band andthe bandwidth of the unknown uplink component band are the same.

However, in this case, depending on the relationship between the actualfrequency bandwidth of an uplink component band and the frequencybandwidth of a downlink component band, the size of Format 1A a basestation actually uses, and the size of Format 1A assumed before aterminal receives information of an uplink component band, may differ.To avoid this problem, only scheduling information for a special BCH forreporting a frequency location or a frequency bandwidth of an uplinkcomponent band can be transmitted in a special format other than Format1A.

Each embodiment mentioned above explains an example when the presentinvention is performed by hardware, but the present invention can beimplemented with software.

Furthermore, each function block employed in the description of each ofthe aforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of an FPGA (FieldProgrammable Gate Array) or a reconfigurable processor where connectionsand settings of circuit cells in an LSI can be regenerated is alsopossible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The disclosures of Japanese Patent Application No. 2008-306742, filed onDec. 1, 2008, and Japanese Patent Application No. 2009-079674, filed onMar. 27, 2009, including the specifications, drawings and abstracts, areincorporated herein by reference in their entirety.

INDUSTRIAL APPLICABILITY

The radio terminal, radio base station, channel signal forming methodand channel signal receiving method of the present invention are usefulto prevent the quality of downlink assignment control information fromdegrading.

1. A user equipment (UE) comprising: circuitry, which, in operation,detect control information, which is mapped on a UE specific searchspace in a first component carrier and which is transmitted from a basestation, based on a first basic information size of control information,wherein the first basic information size is determined by a firstdetermining method, which is different from a second determinationmethod for determining a second basic information size of controlinformation mapped on a common search space in the first componentcarrier and which is different from a third determination method fordetermining a third basic information size of control information mappedon a search space in a second component carrier that is different fromthe first component carrier; and a transceiver, which is coupled to thecircuitry and which, in operation, communicates with the base stationbased on the detected control information.
 2. The UE according to claim1, wherein the third basic information size is determined according to alarger one of a first information size determined from a downlinkbandwidth of the second component carrier and a second information sizedetermined from an uplink bandwidth of an uplink component carrier. 3.The UE according to claim 1, wherein the first basic information size isdetermined according to an information size determined from a bandwidthof the first component carrier.
 4. The UE according to claim 1, whereina number of one or more uplink component carrier(s) assigned to the UEis less than a number of two or more downlink component carriersassigned to the UE.
 5. The UE according to claim 1, wherein a number ofone or more uplink component carrier(s) and a number of one or moredownlink component carrier(s) assigned to each user equipment areasymmetric.
 6. The UE according to claim 1, wherein the first componentcarrier is a component carrier other than a basic component carrier. 7.The UE according to claim 6, wherein the basic component carrier isarbitrarily assigned to each user equipment, and the first basicinformation size for blind decoding in the first component carrier isindependently set for each user equipment.
 8. The UE according to claim1, wherein the first component carrier is a component carrier in whichuplink allocation information is absent.
 9. The UE according to claim 1,wherein when a number of one or more uplink component carrier(s)assigned to the UE is less than a number of two or more downlinkcomponent carriers assigned to the UE, the control information mapped onthe common search space is transmitted only in a portion of the two ormore downlink component carriers.
 10. The UE according to claim 9,wherein the portion of the two or more downlink component carriers is abasic component carrier.
 11. The UE according to claim 1, wherein when anumber of one or more uplink component carrier(s) assigned to the UE isless than a number of two or more downlink component carriers assignedto the UE, uplink allocation information is transmitted only in aportion of the two or more downlink component carriers.
 12. The UEaccording to claim 11, wherein the portion of the two or more downlinkcomponent carriers is a basic component carrier.
 13. A user equipment(UE) comprising: circuitry, which, in operation, detect controlinformation, which is mapped on a UE specific search space in a firstcomponent carrier and which is transmitted from a base station, based ona first basic information size of control information, wherein the firstbasic information size is determined by a first determining method,which is different from a second determination method for determining asecond basic information size of control information mapped on a commonsearch space in the first component carrier; and a transceiver, which iscoupled to the circuitry and which, in operation, communicates with thebase station based on the detected control information, wherein whenuplink allocation information is absent in the first component carrier,the first basic information size is determined according to aninformation size determined from a downlink bandwidth of the firstcomponent carrier.
 14. A communication method comprising: detectingcontrol information, which is mapped on a user equipment (UE) specificsearch space in a first component carrier and which is transmitted froma base station, based on a first basic information size of controlinformation, wherein the first basic information size is determined by afirst determining method, which is different from a second determinationmethod for determining a second basic information size of controlinformation mapped on a common search space in the first componentcarrier and which is different from a third determination method fordetermining a third basic information size of control information mappedon a search space in a second component carrier that is different fromthe first component carrier; and communicating with the base stationbased on the detected control information.
 15. A communication methodcomprising: detecting control information, which is mapped on a userequipment (UE) specific search space in a first component carrier andwhich is transmitted from a base station, based on a first basicinformation size of control information, wherein the first basicinformation size is determined by a first determining method, which isdifferent from a second determination method for determining a secondbasic information size of control information mapped on a common searchspace in the first component carrier; and communicating with the basestation based on the detected control information, wherein when uplinkallocation information is absent in the first component carrier, thefirst basic information size is determined according to an informationsize determined from a downlink bandwidth of the first componentcarrier.